Process of applying reaction plating



March 17, 1953 s. KRONTHAL 2,631,949

PROCESS OF APPLYING REACTION PLATING Filed Jan. 13, 1950 a jm dz'; "7532 22,.

INVENTOR= SIDNEY KRONTHAL ATTORNEY.

Patented Mar. 17, 1953 UNITED STATES PATENT OFFICE This :invention relates to. methods andfmeans for mechanically applying or depositing any metal or metal compound of the electro-chemical series, as well'as metal alloys, to various selected objects and surfaces.

The main object of my invention is to deposit metals, non-metals and the like, as well as alloys, upon the selected objects .or surfaces without using an external electric current or "anode in any form.v

An ancillary object is to deposit metals, alloys and the-like upon the selected objects or surfaces without immersion thereof in a bath of electrolyte or using tanks or any other electroplating paraphernalia.

Awvery important object is. to provide a method and definite means for depositing finely pulverized metals, alloys and metal compounds and the:

like in the form of a smooth, coherent'and adhering deposit or plating on the selected surfaces withoutthe use. of strong acids-or salts of strong acids.

Another important object is to have a method and means for depositing metals, metal alloys and compounds as a firm and continuous deposit or plate on the selected surfaces or objects at room temperature, and without fusion or, application of hea-t in any manner or form.

Av prominent object of this invention is to automatically eliminate the chemical 'filmof oxide, basic carbonate or hydrogen sulphide or derivativethereof on metal surfaces :to be "plated, by means of :the alkali metal base or carbonate and/or silicic acid oranhydrous boric acid inaqueoussolution used for the plating of the metal surface involved.

It is" also an important object of my invention to plate-the selected objects and surfaces with metals, alloys and the like, as indicatedby means ofan ionic reaction of the latter infinely divided 1 formain the "presence of water. It isxa'definite objectof the invention to have such a-method and means for plating "metals,

form-pf the metal or alloy to be deposited uponthe selected surface together with "pure water in thepresence' of boric acid 'anhydride or silicic' acid and/or a base or hydroxide or carbonate 'of atleast one '.of the five alkali metals simultaneously applied in. aqueous solution v.or in the water mentioned, and thus obtain .a micro-ionic.

chemical, electro-potential galvanic 'thermo-action or electro-hydrolysis by combination of the water and powdered alkali and heavy metals and non-metals :and materials, which by being brought together and applied to said surface provide thementioned inter-action spontaneously throughlthe friction occurring between the crystals of .the materials thus striking against each other and against the surface to be plated.

It is evenan object to have such methods and means for plating selected surfaces of various articles such as ornaments, parts of art objects, parts of cutlery articles, parts of furniture,

cplumbing, automobiles and machinery without taking any of such objects apart or dismantling anything "nor immersing the same in baths, but instead depositing the metals, alloys or metal compounds and the like in situ by applying the water and/oraqueous suspension or dispersion of-fisuch metallic material with an alkali base and/or a-weak acid such as anhydrous boric acid or silicic acid.

A convenient object if my invention is'to apply the metallic material in fine, initially dry metallic powder bymeans of aknife, spatula, dauber or roller, orby means of apowder blower simultane ouslydirecting :an air borne-blast of the metallic powder at the surface to be plated while also directing at least one stream, jet or spray of water with the boric acid anhydride or silicic acid in solution-to the same surface, with or without the oxide, hydroxide, bicarbonate of at least one :of the :five alkali-metals.

A desirable object of the invention is toinclude certa'in means for controlling the colors of 'the metallic deposit or plate by using finely divided, pulverized orpowdered aluminum, zinc,- tin,'--.chromium or manganese, for light colors; copper :for reddish-color and brass for yellow coloror shades; as desired.-

A; practical object is, of :course-to use as a means for depositing metals, alloys, metal and andmeans included within the purview of the same, some ,non limiting "examples of apparatus or applying devices useful for practising some of the principles ofithezinvention are illustrated on the accompanying drawing forming part hereof, and in which:

Figure :-1 :is :aigeneral -view-of one method of practising my invention, by :using a knife, spatula or "applying tool and means for simultaneously applying water or solution to the object or surface to he platedp.

spray of water and/or solution may converge,

and simultaneously be directed to a portion the surface intended to be plated;

Figure 4 illustrates how three or more sprays or jets of water and/or solution as well as of metallic powder may be simultaneously directed against a selected spot upon the surface of the object to be plated as by a cold metal spray.

Throughout the views, the same parts are indicated by the same numerals.

All those skilled in the art of electro-plating, galvanoplasty, mirror silvering, hot galvanizing and molten metal spraying and the like, are well aware of many limitations and disadvantages in these arts which are taken for granted as unavoidable even though in some instances they are serious.

Among such disadvantages must be noted unnecessary expense, waste of time, effort and materials, bulk and mess associated with tanks and vats containing electrolytes that are often very poisonous, waste of space, and a generally unhealthy atmosphere in plating plants, not to mention the waste of power occurring in such plants. Furthermore, the surfaces of objects tobe plated must go through a preliminary cleaning treatment and frequently additional treatment to prepare the same for receiving the intended plate or deposit.

Thela'st of above statements merely outline the most prominent features of the problem of applying a reguline metal deposit in the form or a continuous adherent plate to objects or portions thereof, which problem has for a long time formed a burden to indutry and a formidable challenge to anyone who would attempt to simplify the entire procedure and reduce the disadvantages and difficulties involved in these fields.

Upon carefully considering this problem, it has occurred to me that an entirely new approach to the subject of metal plating and related arts is essential to make the desired progress possible. As a result of such consideration, coupled with due investigation and certain discoveries, I have succeeded in eliminating at one sweep all of the enumerated disadvantages and instead fulfilling the foregoing objects in a practical manner, as will now be set forth in further detail.

Hence, in the practice of my invention, and referring again to the drawing, a small amount, say about a quarter of a teaspoonful or less of a finely divided metal, for example, aluminum of from 200 to 500 per inch mesh, preferably of about 350 mesh is applied at 5 on a surface 6 of an object 1 to be plated, by means of a knife, spatula, dauber, spoon or applicator 8. Of course, any other one or more finely powered metals may be thus applied, such as zinc or tin with copper, sliver, nickel, etc. Simultaneously with the application of the powdered metal, water 3 is floated, dropped or otherwise applied to the same surface from a dropper or poured from a vessel 2, together with finely divided anhydrous boric acid or silicic acid and/or the oxide, hydroxide or bicarbonate of at least one of the five alkali metals, lithium, sodium, potassium, rubidium and caeslum. The water is preferably of distilled quality and may have the acid and/or the base of the al- 4 kali metal actually dissolved therein to form a solution in which the concentration of the acid ranges from a trace or about 1% up to saturation, when acid is used, and when the base is used, the same may also range from about 1% to saturation, and when both are used, the one may .beof greater concentration than the other, if

desired. In fact, I find that both silicic acid and boric acid when used together in at least semisaturated solution work very well in the presence of a semi-saturated solution of the alkali base.

The acid is definitely a weak mineral acid, while the base is in each case very strong, and these constituents of the means used for the plating reaction all serve to ionize the solution and cause the metal powder to form a dispersion, as will be further explained. Three weak acids are available for the present purpose, anhydrous boric acid, silicic acid, and phosphoric acid, all being mineral acids.

While applying the plating composition thus far outlined, I contrive to cause the resulting solution to drain off the surface being plated so that the metal powder will be directly deposited thereon without merely floating on top of the fluids reacting to produce the plating action. Thus, in order to control the action and promote the desired reaction, applicator B is used to lightly rub the metal on the surface 6 with the active fluids present, and thereby virtually apply friction to the metal powder to promote ionization and spontaneous electrohydrolysis, resulting in the adhesion of the metal to surface 6 in a coherent metal plate merging apparently molecularly with this surface so as to be effectively bonded thereto. As shown in Figure 2, the roller 4 may be used for the same purpose instead of applicator 8, the remaining features being the same. No previous preparation of surface 6 has been required, and especially if it is a metallic surface, the usual chemical film of oxide, basic carbonate or hydrogen sulphide compound or derivative is automatically dissolved and removed by the powerful action of the weak acid and strong base with the water, when the metallic dispersion is being deposited on the surface 6.

At this point it may be well to note that the boric acid used is imperatively the anhydride, either dissolved in the water used or applied simultaneously in pulverized form with the water so that it goes into solution at once, 7

the ordinary boric acid being indifferent for the present purpose. The acid and/or the alkali base ionizes the water so that the metal plating occurs as though directly electrically plated by means of an outside source or current, yet without using any conventional electrical means, connections, solid anode nor electrolytic bath.

As already mentioned, the acids and bases may be used in substantially any concentrations in the resulting solutions, ranging from one or two percent to saturation, but ordinarily, in the solution involved, the boric anhydride, silicic or phosphoric acids are used in from a semi-saturated to substantially saturated solution, the same being true of the alkali base when also used or used alone in the water. The acids and bases may be used in different proportions, so that, for example, the one or more acids present may constitute only a few percent of the solution, from two to twenty percent, and the alkali base ten to forty percent, or the proportions may be reversed. Also, one acid, the boric anhydride may be present in from one percent to about twenty percent of saturation, :the :silioic acid, when also .used present in :f-rom @ten to sixty 5133 081117 of set-- uration, :and the base may ,be of :xsubstantially fifty percent concentration, or any other proportions used, :as :found -best in particular cases. One :formula .of {the boric acid anhydride may be :referred to, namely, B203 which becomes associated with :3 molecules of water, ;3I-IzO.,"- while a formula :forithe silicicacidzis HzSiOz which also becomesassociatedwvith za'zmoleculeof wateriHzO. The formulas for the bases are too 'well known to require specific mention by way of 261181111031 representation.

fit ;is, of course obvious that when :using higher concentrations of :the mentioned weak :mineral acids capable :of ionizing water :andlor of the alkali .metal bases with .larger amounts of the powdered metals to be deposited, the action :is more vigorous and the plating ibecomes heavier than if small amounts of :metal are used "with weak solutions.

While it is thus Iposslble to apply the :metal plate by using a manually held applicator, I have :found .it more practical "to "apply the powdered metal by 'way :of an air borne jet andth'e waterand/or solutions by way of one or more air borne "jets or sprays "directed to the same point upon the surface to be 'plated against which the metal jet impinges simultaneously 't'herewi'tl'l. Such handling of the metal powder and solutions lends itself 'to very nice adjustment, so that the result is virtually a cold :meta'l spray applied to the mentioned-surface.

For {such 'more or less automatic spray plating, a'pair of nozzles shown in Figure 8 willservefithe one nozzle 9 having a supply of solution In escaping as a jet or spray -H directed to the surface l2 of an object 13, while a "second nozzle [4 has a supply l5 of powdered metal issuing at l6 as a jet directed to the :same spot on surface l2. The two jets or sprays converge "and thus merge on the same point upon the ,surface 12 intended to be plated, this surface being preferablyinclined .or arranged to drain 'ofith'e solution as soon as it has served to deposit the metal.

Thus, the solution in one form "includes from onep'ercent of boric anhydride'to saturation, 1% tosaturated solution of silicic acid, and from 1% to saturatedosolution of sodium hydroxide or bicarbonate.

.Anotheriorm of the solution includes from 1% to saturation of anhydrous boric acid with from 1,% to saturation of the sodium hydroxide .or bicarbonate without any other acid, but only pure water for the solution.

A third term of solution includes jrom 1% .to saturation of silicic acid with .from 1% to eaturation .of the alkali hydroxide or bicarbonate. The phosphoric acid may replace the ,silicic acid in this form of thesolution when (desired.

Another ,form :of solutionincludes ,from 1% to saturation of the oxide, hydroxide ,or bicarbonate of at least one of the five alkali metals, .as already mentioned, with pure water.

With any one of the above solutions containing pure or distilled. water, as indicated at in in Figure .3 and sprayed or projected ,in a Jet -11 toward surface or object I3, I ,also groject ,a -jet N5 of the powdered metal I15 to the same spot l2 on object 13. The nozzles 9 and 14 thus spraying the Jets are advantageously :secured together and each provided with its own reservoir for the solution or metal powder, as the case may be, .Whilfi :an :air pressure hose .rrom anair 6 compressor or z-tank is connected to both inmvide compressed air to propel the metal :and solution simultaneously toward spot it bein mated. The pulverized :metal :is preferably at least one of the amphoteric metals aluminum,

zinc or tin, indicated at A15 and may :also in-- clude tone :or more further metals :in any sic si-red proportion such :as copper, silver, znickel, chromium :and the like, so long as these metals are so ifinely divided :as ;to be at :least 200 :mesh. and preferably about .350 mesh tor even ifiner. Also, :with the :amphoteric .ameital, i may use pulverized alloys, .FfiOl example, :brass or :bronze or any other ,to dorm the .main plate :upon object l3, @the ampho'tericsmetahmakin'g the plating-rob fective.

When the aqueous solution zthus meets :the metal powder in converging "jets 11 and 2115 181- spot .42 on object 13 :to be eplated, andmmediate reaction occurs, depositing the metal or metals thus :sprayed :as :a continuous :plate. "the plate deposits, the nozzles are held rpositlon long enough to make the platesufilciently heavy to :be practical, say for a minute nor .tWO, and the nozzles are then shifted aside to tfresh surface to ;be plated. As t-nozzles 7.9 and M vfare eprei'crab-ly secured together, they are easily.moue:d urccurately together, and as the platmg proceeds, the entire :surface :is thus "progressively :metail coated .or :plated with a :coherent rcontinuous tadhering .coat of metal.

.The .platin'g :occurs :as result ot a. aclrcle so! reactions in whichrthe amphoteric metalrorsmetals form *a inundation :plate with which #0). union which the further selected "metal or metals the come plated. "The amphoteric :m-etal used-mine, aluminum .or tin, due to its inherent basic and acidic properties, :w-il-l form a colloidal dispensi-on in the solution, whether present vlin the pulverized metallic form :or in the form of hydroxide. This -=collo'idal dispersion is dissociated :by contact with ions of opposite charge such as the hydrogen ion or oppositely charged metallic particles. The metal particles of the reaction become neutralized and deposit-as a plate on the surface 12 to be plated. -The color'o'f the plate is :readily controlledby the metals selected, copper for reds andp'ink shades, tin, aluminum with zinc for white; say about 5% *of'zinc, 5% of tin, and of aluminum forms a "practical proportion resulting in a white or silvercolior.

As seen in Figure 4, a group H of three or more nozzles I8, 19 and 20 are associated together to form a spraying unitserving to spray or project a jet '2] of aqueous solution ranging from a to saturated solution of boric acid anhydride and/or of silicic acid, an air borne jet 22 of a 1% to saturated solution of analkall metal .base such as sodium hydroxide or :bicarbonate .or a i-blast of pulverized i-hscdroxide, oxide or bicarbonate off the alkali .me'talmay form the jet Q22 directed like jet 2.1 at thespot Z24 .onsob- J'eclt] 'fromsupply 10. .At thesame time, .a further air home jet 13 issues from nozzle 20 of one .or more pulverized .metals .l5 already enumerated, being projected ag inst the .same spot '24 with the other jets. ZIfhemetah-powder is dry and when two or more metals are aised, onemay beprqjected through .nozzle 20 and the other .metal or metals may similarly "be lpro ect' ed simultaneously through .-a ,further nozzle rinot shown.) while the nozzles v-I 8 and 419 may =.de.1iver a jet-of water and 1a jet-of pulverizedboric acid anhydride and oxide, respectively. who uiver- I ized anhydride maybe mixed with -dry 'p'uIveriz'ed oxide, hydroxide or bicarbonate of one of the alkali metals. The three nozzles merely represent a. plurality of nozzles which may be used, as many as may be required for the different jets which may be desired, and the number may therefore vary, but in each case,-every nozzle is directed to the same spot on the surface of the object to be plated. In addition, it is desirable to have independently operable valves 25, 2B and 21, etc., on the nozzles to regulate the flow of material as propelled by the compressed air supplied to the nozzles'to the plating zone. The

air pump or tank, hose, nozzles and reservoirs and valves all promote the effectiveness of the invention although not forming actual part thereof, and illustrate a preferredform of apparatus for applying the plating, due to its convenience and latitude of adjustment and flexibility in use.

In the reaction or plating zone, the reaction and grouping of the materials virtually set up a. large number of local action electric cells, each of which deposits its quota of metal. For ex-' ample, the boric acid'anhydride solution or silicic acid solution forms an electrolyte, the al-- k-ali metal of the base compound forms an anode. and partly an electrolyte with the acid solution; the amphoteric metal or surface receiving the plate forming a cathode,.while the friction or agitation caused by mechanically applying thev components of the reacting materials resulting in theplating action. furnishes. potential to. the.

metal particles effecting the deposit of the plate from the metal powder.

'The bases used in the invention are limited to the strong bases of the five alkali metals, while the acids, boric acid anhydride, silicic and phosphoric acids are all weak compared to such acids as sulphuric, hydrochloric and nitric acids which latter are definitely not useful for the present purpose. Of the couples of dissimilar metals used, those giving the greatest difference of potential are the most efi'ective to provide the plating reaction, namely, aluminum, zinc and tin in powder. These metals thus work well together with each other or with another metal in groups of two or more for the amphoteric metal. For example, aluminum is slightly attacked by the alkali metal base to-form negative AlOH ions in active condition to precipitate aluminum when coming into contact with the other metal present in powdered form, which discharges the negativecharge of the ions and causes metal to be deposited on the surface to be plated. At the same time, the metal crystals receive a negative charge from the ions sufiicientv toprecipitate them with the aluminum uponthe same surface while becoming neutral. f v

I In contrast with ordinary electroplating, in this invention no solid or continuous anode is used and the surface upon which the plating occurs need'not be a conductor, as a local plating current is produced in the solution due to the presence of the amphoteric metal as in at'least one stage the cathode,'and theother powdered metal as the anode which deposits without the neces sity of being reduced from any salt.

The weak acid serves as a bufier for maintaining the composition being applied under control at a neutral level or pH value and keeping the solution inionic condition. Solutions containing amphoteric hydroxides are strongly hydrolyzed with weak-acids and thus ionized, and when dissolved" in water, form precipitates of theamphoteric hydroxides which as metal particles become negatively charged as already mentioned. By contact with free hydroxyl radicle ions and with the crystals of the metal powder in the solution, the precipitated metal particles which are 'negatively charged attract the positively charged crystals of the metal powder and lose their charge and then plate the object or selected surface. The amphoteric metal thus forms a" foundation plate and any other metal also deposited accompanies and plates with the same. The reactions involved occur in a series ina solution always including water.

'If the micro-electro-chemical plating reaction occurs in a jar with acid and/or alkali metal base and metal powder is added; or if the reacting components are brought together to form a shallow pool on the surface to be plated; or even if these components are brought together as an active smear or a film on the surface involved, yet the reaction proceeds in the same manner as already outlined in the foregoing. The metal powder ordinarily floats on the surface of the fluid, to become a dispersion, the bulk of the fluid forming an active solution of the alkali metal base and/or the weak acid or acids with whatever portion of the amphoteric metal has been formed into a hydroxide salt in the solution, and the bottom layer of precipitating and depositing metal.

In a normal solution of acid or alkali base. the amphoteric colloid hydroxide will precipitate at the bottom of the solution against or upon the surface to be plated to become negative and attract the metal particles of the powder whereby it will be neutralized and will immediately plate the surface. When, however, the alkali base is present in excess, the amphoteric hydroxide particles are dispersed and thus fail to precipitate and are acid in reaction and colloidally dispersed in the solution. If the alkali base is less than normal for the solution or absent, the amphoteric hydroxide becomes ionic and forms a base controlling the solution in the presence of the weak acid which is one or more of the three, boric acid anhydride, silicic or phosphoric acids.

The same principles expressed in formulas will be as follows, for example when the alkali base is in excess, the reaction is Al(OH)3+alkali base=colloidal dispersion and reacts as an acid;

When the amphoteric hydroxide is in normal solution, the reaction is Al(OI-I)3+acid=acid metal+water which is ionic and reacts as a base;

However, when the alkali metal base is present in less than normal for the solution, the reaction is Al (0H)s+alkali base=Al(OH)3 precipitates.

When powdered amphoteric metal such as aluminum is attacked by sodium hydroxide, for example, which is a strong base, the reaction is;

alkali aluminate (NaAl(OH) )+weak acid +HzO+Al(OH)3+weak acid=(OI-I)3 which forms water by being neutralized with H- ions and aluminum metal becomes negatively charged so that it goes to the bottom of the reaction zoneand plates the surface to receive the deposit while losing its charge. 1

From the foregoing, it is evident that thereare Several separate reactions occur substantial- 1y simultaneously to form a series or chain. of.

instantaneous connecting reactions of high velocity;

Both electrolysis and hydrolysis are involved therein;

The deposit or plate is the result of a number of distinct reactions acting virtually instantly to cause the completed process to be substantially spontaneous and automatic;

The metals used in powdered form present maximum electrode surfaces to the solution or reacting fluids;

Because of the very large electrode surfaces exposed to the solution, ionization of the latter will be practically instantaneous and complete;

During the reactions simultaneously occurring, galvanic currents and charges are instantly generated;

The total conducting current of the several combined reactions, such as derived from friction, thermo-couple effect, chemical action, etc., is the measure of the potential causing the flow of electrons through the solution or fiuid present;

The finer the subdivision of the metal powder with resulting increase of electrode surface exposed to the reactions, the finer is the colloidal dispersion in the solution, and the more easily and quickly is the deposit effected;

Obviously, the amount of pulverized metal or alloy used for effecting the plating reaction upon the selected surface is suflicient for at least partly chemically and electrically balancing the weak mineral acid and/or the strong base to react therewith and simultaneously deposit the metal as a continuous adhering plate. In fact, the ionizing compounds virtually form catalysts, so that the actual proportions used are of lesser importance, as the reaction will take place in any case in the presence of the pulverized metal and effect the deposit of the latter as the plate upon the surface to be plated. The amounts of the ionizing compounds and the pulverized metals involved by their relative proportions thus merely determine the inten ity but not the quality of the reaction obtained.

Manifestly, variations other than those indicated may be resorted to, and features and steps may be modified or used without others within the scope of the appended claims.

Having now fully described my invention, I claim:

1. Process for producing a plating reaction and depositing a metal or alloy plate upon a selected surface independently of the chemical nature of the latter, which process consists in initially bringing together from separate material supplies into reacting association upon the selected surface, water with a strong base of at least one of the alkali metals and at least one weak acid of the class consisting of anhydrous boric acid, free uncombined silicic acid and free phosphoric acid to form a local solution ranging from a 1% concentration to saturation, and a simultaneously applied supply of finely pulverized metal of a fineness of at least 200 mesh per inch to react with the resulting solution formed upon said selected surface and plate metal directly on the latter.

2. Process according to claim 1, wherein the water, base and acid compounds and the metal powder are sprayed upon the metal surface in converging jets, one jet being formed exclusively of the metal powder borne upon a jet of compressed air.

3. Process according to claim 2, wherein the object of the selected surface is disposed in such position that said selected surface is inclined to promote drainage of water off the same.

l. Process according to claim 1, wherein the metal powder includes an amphoteric metal.

5. Process according to claim 1, wherein the pulverized metal includes at least two metals, one of which is amphoteric.

6. Process according to claim 1, wherein the water with the strong base and weak acid and the metal powder are sprayed upon the selected surface in such manner that the metal powder first meets the water and the base and acid upon said selected surface.

7. Process according to claim 6, wherein at least two metals are included in the metal powder, one metal being amphoteric.

8. Process according to claim 6, wherein the water, the strong base and weak acid as well as the pulverized metal are sprayed in a plurality of jets upon the selected surface to converge on the latter, the metal forming a separate jet which meets the Water and the base and acid upon said selected surface.

9. Process according to claim 8, wherein at least two metals are included in the pulverized metal and one is amphoteric.

10. Process according to claim 8, wherein the pulverized metal is amphoteric.

11. Process according to claim 6, wherein the pulverized metal is amphoteric.

12. Process according to claim 6, wherein the spraying is performed by means of a plurality of converging jets.

13. Process according to claim 6, wherein a multiple spray device having separate material supplies is used to spray the water, strong base, weak acid and metal powder from said material supplies in a plurality of converging jets upon the selected surface.

14. Process according to claim 13, wherein the plural jets are individually fed from the separate supplies of water, strong base, weak acid and pulverized metal.

15. Process for producing a plating reaction and depositing a metal or alloy plate upon a selected surface independently of the chemical nature of the latter, which process consists in initially bringing together from separate sources of supply into reacting association upon the selected surface, water with two mineral ionizing compounds comprising a strong alkali-metal reagent and a free uncombined weak acid to form an active ionized solution upon said selected surface ranging from a 1% concentration to saturation and a simultaneously applied supply of finely pulverized metal of a fineness of at least 200 mesh per inch to react with the ionized solution and plate directly upon said selected surface.

SIDNEY KRONTHAL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,380,847 Sorensen June 7, 1921 2,136,024 Schneider Nov. 8, 1938 2,150,789 Smith Mar. 14, 1939 2,161,104 Smith June 6, 1939 2,355,186 Fischer Aug. 8, 1944 2,509,875 McDonald May 30, 1950 

1. PROCESS FOR PRODUCING A PLATING REATION AND DEPOSITING A METAL OR ALLOY PLATE UPON A SELECTED SURFACE INDEPENDENTLY OF THE CHEMICAL NATURE OF THE LATTER, WHICH PROCESS CONSISTS IN INTIALLY BRINGING TOGETHER FROM SEPARATE MATERIAL SUPPLIES INTO REACTING ASSOCIATION UPON THE SELECTED SURFACE, WATER WITH A STRONG BASE OF AT LEAST ONE OF THE ALKALI METALS AND AT LEAST ONE WEAK ACID OF THE CLASS CONSISTING OF ANHYDROUS BORIC ACID, FREE UNCOMBINED SILICIC ACID AND FREE PHOSPHORIC ACID TO FORM A LOCAL SOLUTION RANGING FROM A 1% CONCENTRATION TO SAUTRATION, AND A SIMULTANEOUSLY APPLIED SUPPLY OF FINELY PULVERIZED METAL OF A FINENESS OF AT LEAST 200 MESH PER INCH TO REACT WITH THE RESULTING SOLUTION FORMED UPON SAID SELECTED SURFACE AND PLATE METAL DIRECTLY ON THE LATTER. 